TRIAL IMPLANT

Abstract

TITLE OF INVENTION : TRIAL IMPLANT The present disclosure discloses a trial implant (100) comprising a liner (110), a base (150), and a cam shaft (131) disposed in the liner (110). The liner (110) is configured to interface with a prosthetic glenoid ball. The base (150) is configured to be removably coupled to a stem implanted within the humerus bone. The base (150) is slidably coupled to the liner (110). The rotation of the cam shaft (131) causes a change in an axial displacement of the liner (110) with respect to the base (150). Fig. 1

Specification

Description: FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10 and Rule 13)

1. TITLE OF THE INVENTION:
TRIAL IMPLANT
2. APPLICANT:
Meril Corporation (I) Private Limited, an Indian company of the address Survey No. 135/139, Muktanand Marg, Bilakhia House, Pardi, Vapi, Valsad-396191 Gujarat, India.




The following specification particularly describes the invention and the manner in which it is to be performed:

 
FIELD OF INVENTION
[001] The present disclosure relates to a trial implant. More particularly, the present disclosure relates to a trial implant for shoulder arthroplasty.
BACKGROUND OF INVENTION
[002] The glenohumeral joint is the highly mobile ball-and-socket joint that connects the upper arm bone (humerus) to the shoulder blade (scapula). It allows for an exceptional range of motion, but it is also prone to instability due to the shallow socket. Surrounding muscles, ligaments, and tendons work together to provide support and facilitate movement. There are several medical conditions that are associated with the glenohumeral joint such as acute proximal humerus fractures, post-traumatic glenohumeral osteoarthritis, chronic irreducible shoulder dislocation, etc. The patient suffering from any of the aforementioned medical condition may face several complications such as stiffness in the joint, loss of partial or full range of motion, pain during movement and so forth.
[003] For the treatment of such medical conditions, a doctor may suggest the patient undergo reverse total shoulder arthroplasty (RTSA). In RTSA, the ball part is implanted on the scapula and the socket is implanted on the proximal humerus.
[004] The arrangement of the socket and the ball is positioned at an offset which may depend on the anatomy of the patient to obtain the maximum range of motion. Conventionally, a trial implant is used to determine the offset before final implantation. For every offset, there is a separate trial implant. The medical practitioner has to try a number of trial implants before deciding an optimal implant with an offset that offers the maximum range of motion. Thus, the conventional method of determining the offset of the ball and the socket arrangement may increase the overall time required for the surgery and may make the procedure cumbersome.
[005] Hence, there is a need for a trial implant that overcomes the shortcomings, associated with the trial implants known in the art.
SUMMARY OF INVENTION
[006] Particular embodiments of the present disclosure are described herein below with reference to the accompanying drawings, however, it is to be understood that the disclosed embodiments are merely examples of the disclosure, which may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure.
[007] The present disclosure discloses a trial implant comprising a liner, a base, and a cam shaft disposed in the liner. The liner is configured to interface with a prosthetic glenoid ball. The base is configured to be removably coupled to a stem implanted within the humerus bone. The base is slidably coupled to the liner. The rotation of the cam shaft causes a change in an axial displacement of the liner with respect to the base.
BRIEF DESCRIPTION OF DRAWINGS
[008] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the apportioned drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the disclosure is not limited to specific methods and instrumentality disclosed herein. Moreover, those in the art will understand that the drawings are not to scale.
[009] Fig. 1 depicts an exploded view of a trial implant 100, in accordance with an embodiment of the present disclosure.
[0010] Fig. 2a depicts a perspective view of a liner 110, in accordance with an embodiment of the present disclosure.
[0011] Fig. 2b depicts another perspective view of the liner 110, in accordance with an embodiment of the present disclosure.
[0012] Fig. 2c depicts yet another perspective view of the liner 110, in accordance with an embodiment of the present disclosure.
[0013] Fig. 3a depicts a perspective view of a base 150, in accordance with an embodiment of the present disclosure.
[0014] Fig. 3b depicts another perspective view of the base 150, in accordance with an embodiment of the present disclosure.
[0015] Fig. 4 depicts an exploded view of an adjustment assembly 130, in accordance with an embodiment of the present disclosure.
[0016] Fig. 5 depicts a perspective view of an assembly of the humeral base 150 and the adjustment assembly 130, in accordance with an embodiment of the present disclosure.
[0017] Fig. 6 depicts a perspective view of the assembly of the liner 110 and the adjustment assembly 130, in accordance with an embodiment of the present disclosure.
[0018] Fig. 7a depicts the assembly of the base 150 and the adjustment assembly 130 in a first offset configuration of the trial implant 100, in accordance with an embodiment of the present disclosure.
[0019] Fig. 7b depicts a cross-sectional view of the trial implant 100 in a first offset configuration, in accordance with an embodiment of the present disclosure.
[0020] Fig. 7c depicts the assembly of the base 150 and the adjustment assembly 130 in a second offset configuration of the trial implant 100, in accordance with an embodiment of the present disclosure.
[0021] Fig. 7d depicts a cross-sectional view of the trial implant 100 in the second offset configuration, in accordance with an embodiment of the present disclosure.
[0022] Fig. 7e depicts the assembly of the base 150 and the adjustment assembly 130, in a third offset configuration of the trial implant 100, in accordance with an embodiment of the present disclosure.
[0023] Fig. 7f depicts a cross-sectional view of the trial implant 100 in the third offset configuration, in accordance with an embodiment of the present disclosure.
[0024] Fig. 8 depicts an exemplary method 200 of using the trial implant 100, in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF ACCOMPANYING DRAWINGS
[0025] Prior to describing the invention in detail, definitions of certain words or phrases used throughout this patent document will be defined: the terms "include" and "comprise", as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "coupled with" and "associated therewith", as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have a property of, or the like. Definitions of certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases.
[0026] Reference throughout this specification to "one embodiment," "an embodiment," or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean "one or more but not all embodiments" unless expressly specified otherwise. The terms "including," "comprising," "having," and variations thereof mean "including but not limited to" unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms "a," "an," and "the" also refer to "one or more" unless expressly specified otherwise.
[0027] Although the operations of exemplary embodiments of the disclosed method may be described in a particular sequential order for convenient presentation, it should be understood that the disclosed embodiments can encompass an order of operations other than the particular sequential order disclosed. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment and may be applied to any embodiment disclosed herein. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed system, method, and apparatus can be used in combination with other systems, methods, and apparatuses.
[0028] Furthermore, the described includes, advantages, and characteristics of the embodiments may be combined in any suitable manner. One skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific includes or advantages of a particular embodiment. In other instances, additional includes and advantages may be recognized in certain embodiments that may not be present in all embodiments. These includes and advantages of the embodiments will become more fully apparent from the following description and apportioned claims or may be learned by the practice of embodiments as set forth hereinafter.
[0029] In accordance with the present disclosure, a trial implant is disclosed. The trail implant of the present disclosure is utilized during a reverse total shoulder arthroplasty (RTSA). In a RTSA implant procedure, the glenoid cavity is replaced with a prosthetic glenoid ball, while the humeral head is replaced with the trial implant of the present disclosure. The trial implant is used to accurately position the humeral plate of the prosthesis with respect to the prosthetic glenoid ball implanted at the glenoid cavity. The multiple offset positions allowed by the trial implant provides a convenient and less traumatic solution for adjusting the position of the prosthetic humeral plate with respect to the prosthetic glenoid ball, thus, providing the maximum range of motion to the patient's glenohumeral joint, with the least or no strain on the muscles, ligaments, and tendons of the glenohumeral joint.
[0030] The trial implant is placed on a prosthetic humeral stem that is implanted in the proximal humerus. The face of the trial implant provides an articulating surface to the prosthetic glenoid ball component that is implanted on the scapula to substitute the ball and socket arrangement of the glenohumeral joint.
[0031] The humeral stem and the ball component are to be placed at a vertical or axial displacement offset that offers an optimal range of motion. The offset may be defined as the distance between the center of rotation of the prosthetic glenoid ball engaging interface of the trial implant and the prosthetic humeral stem.
[0032] The trial implant includes a liner, a base, and an adjustment assembly. The liner is placed on the base. The assembly of the liner and the base forms the trial implant. The trial implant can be toggled between multiple offsets using an adjustment assembly. The trial implant has an initial height that is defined by the combination of the height of the base and the liner. The height of the trial implant can be adjusted using the adjustment assembly that is disposed in between the liner and the base. The adjustment assembly increases or decreases the axial displacement between the liner and the base, to attain different offsets. Thus, the trial implant of the present disclosure is not restricted to a single offset.
[0033] The trial implant can be toggled between multiple offsets which allows a medical practitioner to determine the most appropriate offset for the patient, using a single trial implant. Thus, the use of the single trial implant of the present disclosure reduces the overall time of the surgery. The cost of the surgery may also be reduced as instead of using multiple implants for different offsets, only one implant can be used for multiple offsets. Further, due to the use of the single trial implant, patient trauma is also significantly reduced, as compared to procedures involving multiple separate implants having distinct offsets. The surgical procedure is also simplified by the use of the present trial implant as the medical practitioner does not need to repeat the process of placing and removing multiple trial implants to determine the final offset, optimal for the patient.
[0034] Now referring to the figures, Fig. 1 depicts an exploded view of a trial implant 100. The trial implant 100 includes a proximal end 100a and a distal end 100b. The trial implant 100 includes a liner 110, an adjustment assembly 130, and a base 150. The liner 110 is disposed towards the proximal end 100a of the trial implant 100. The liner 110 provides an articulating surface to the ball component that is implanted on the scapula. The liner 110 may be a single component. Alternatively, the liner 110 may be an assembly of several components.
[0035] The base 150 is disposed towards the distal end 100b. The base 150 is configured to be coupled with the humeral stem component (not illustrated in the figures) implanted in the humerus. The base 150 may be a single component. Alternatively, the base 150 may be an assembly of multiple components. In an embodiment, the base 150 is a single component.
[0036] The adjustment assembly 130 is disposed between the liner 110 and the base 150. The adjustment assembly 130 is a cam assembly, configured to adjust the axial displacement between the liner 110 and the base 150, and consequently the offset of the trial implant 100. The adjustment assembly 130 may include multiple components which together contribute to the offset adjustment operation of the trial implant 100.
[0037] In accordance with Fig. 2a, the liner 110 is shown in a perspective view. The liner 110 is configured to interface with the prosthetic glenoid ball component implanted on the scapula. The liner 110 may be made of a material including, but not limited to cross-linked polyethylene (XPLE), ultra high molecular weight polyethylene (UHMWPE) with vitamin E, and so forth. In an embodiment, the liner is made of ultra high molecular weight polyethylene (UHMWPE). The liner may be fabricated using a method including, but not limited to molding, , Extrusion, Thermoforming and Vacuum Forming, and so forth. In an embodiment, the liner 110 is fabricated using molding. The mating surface (visible in Fig. 2c) of the liner 110 on the proximal end 100a, has a curvature that provides an articulating surface for the ball component. The bottom face of the liner 110 is provided with a plurality of pegs 111. The liner 110 also includes a plurality of first slots 113, a plurality of second slots 115, and a third slot 117.
[0038] The pegs 111 protrude from the bottom face of the liner 110. The pegs 111 are positioned along the circumference of the bottom face of the liner 110. In an embodiment, the liner 110 includes two pegs 111, positioned diametrically opposite to one another. In another embodiment, the liner 110 may be provided with more than two pegs 111 The pegs 111 are employed to slidably couple the base 150 with the liner 110 cam shaft. The pegs 111 mate with the ribs 140 (explained later in conjunction with Figs. 3a and 3b) of the base 150, thus slidably coupling the liner 110 and the base 150. The pegs 111 may have a pre-defined height protruding from the bottom surface of the liner 110. In an embodiment, the height of the pegs 111 may range between 0.5mm and 100mm.
[0039] The liner 110 is provided with a plurality of first slots 113 on the bottom face. The first slots 113 are configured to receive corresponding ones of a plurality of cams 133 of the adjustment assembly 130 (explained later in conjunction with Fig. 4). In an embodiment, the liner 110 includes two first slots 113. The first slots 113 may be positioned at two diametrically opposite positions on the bottom face of the liner 110. In another embodiment, the liner 110 includes more than two first slots 113. In such an embodiment, the first slots 113 may be positioned symmetrically along a diameter of the liner 110. In an embodiment, the first slots 113 have a rectangular profile with beveled or rounded corners. Alternatively, the first slot 113 may have a rectangular profile with sharp corners. The first slots 113 may have a pre-defined depth. In an embodiment, the depth of the first slots 113 may range between 0.5mm and 20mm. In an embodiment, the depth of the first slots 113 is 4mm.
[0040] The plurality of second slots 115 are also provided on the bottom face of the liner 110. The second slots 115 are configured to receive a respective resilient element 135 of the adjustment assembly 130 (explained later in conjunction with Figs. 4 and 5). In an embodiment, there are two second slots 115. In another embodiment, there may be more than two second slots 115. In some embodiments, there are as many second slots 115 as there are pegs 111. Each second slot 115 may be positioned beside the respective peg 111. Such an arrangement allows for uniform distribution of the tensile force applied by the resilient elements 135, to the liner 110 and the base 150. In an embodiment, the second slots 115 are circular in shape. Alternatively, the second slot 115 may have any other shape including but not limited to elliptical, square, and so forth. The second slots 115 may have a pre-defined diameter. In an embodiment the diameter of the second slot 115 may range between 0.5mm and 20mm. In an embodiment, the diameter of the second slots 115 is 5mm.
[0041] The third slot 117 is provided on the bottom face of the liner 110. The third slot 117 may be positioned exactly along or close to a diameter of the bottom face of the liner 110. The third slot 117 is configured to receive a cam shaft 131 of the adjustment assembly 130. The third slot 117 is configured to allow the cam shaft 131 to at least partially rotate within the third slot 117. The third slot 117 may be interconnected with the first slots 113, since the first slots 113 and third slot 117 together accommodate the cam shaft 131, and cams 133. The third slot 117 may have a pre-defined width. In an embodiment, the width of the third slot 117 ranges from 0.5mm to 20mm. In an embodiment, the width of the third slot 117 is 4mm. In an embodiment, the third slot 117 has at least one open end 117a. The open end 117a allows the cam shaft 131 to be rotatable from the exterior of the trial implant 100, for example, through a drive head (shown in Fig. 4). The third slot 117 may have a predefined length. The length of the third slot 117 may range between 0.5mm and 30mm. In an embodiment, the length of the third slot 117 is 15mm.
[0042] Fig. 2b depicts a perspective view of the liner 110. As shown in Fig. 2b, at least one of the pegs 111, is provided with a plurality of cavities namely a first locking slot 111a, a second locking slot 111b, and a third locking slot 111c. In an embodiment, there are more than three locking slots. Each locking slot corresponds to a respective offset i.e., axial displacement of the liner 110 with respect to the base 150. The locking slots (111a, 111b, and 111c) may be employed to lock the liner 110 with the base 150 in a fixed position, i.e. at a particular offset of the trial implant 100. The locking slots 111a, 111b, and 111c may be configured to mate with a plunger ball 139a of a plunger 139 of the adjustment assembly 130 at a respective offset (explained later in conjunction with Fig. 4). In an embodiment, only one of the pegs 111 is provided with the plurality of locking slots 111a, 111b, and 111c. In another embodiment, all the pegs 111 may be provided with the plurality of locking slots 111a, 111b, and 111c. In an embodiment, the locking slots 111a, 111b and 111c have a hemispherical shape. Alternatively, the locking slots 111a, 111b and 111c may have any other shape including, but not limited to circular, oval, and so forth.
[0043] The other peg 111 may be provided with a slot 112 (shown in Fig. 2c). The slot 112 is configured to receive at least a portion of a pin 137. The slot 112 allows the pin 137 to move vertically, while inhibiting sideways motion. In other words, the slot 112 may allow the axial displacement of the liner 110 with respect to the base 150, while preventing or inhibiting the rotational displacement therebetween. The shape of the slot 112 may correspond to the shape of the pin 137. In an embodiment, the slot 112 has a rounded rectangular shape. In an embodiment, the width of the slot 112 corresponds to the diameter of the pin 137. The slot 112 may have a predefined length. In various embodiments, the slot 112 may have a length corresponding to the range of offsets i.e. the difference between the maximum offset and the minimum offset of the trial implant 100. Stated differently, the range of motion of the pin 137 is equal to the difference between the maximum offset and the minimum offset of the trial implant 100. The length of the support slot 112 may range between 0.5mm and 20mm. In an embodiment, the length of the support slot 112 is 6mm.
[0044] In accordance with Figs. 3a and 3b, perspective views of the base 150 are depicted. The base 150 may be removably coupled to a stem (not shown) implanted within the humerus. The base 150 may be made of a material including, but not limited to titanium, cobalt-chromium, stainless steel, or a combination thereof. In an embodiment, the base 150 is made of Titanium. The base 150 may be fabricated using methods including, but not limited to molding, casting, forging, and the same. In an embodiment, the base 150 is fabricated using forging. The base 150 includes a flat portion 150a, a sidewall 150b, and a cylindrical shaft 150c. The cylindrical shaft 150c may be configured to be directly implanted on the humerus or on a prosthetic humeral stem implanted on the humerus. It shall be appreciated that the aforementioned components may or may not be individual components having individual properties.
[0045] The flat portion 150a is provided with a plurality of tray slots 151. In an embodiment, the flat portion 150a has two tray slots 151. The tray slots 151 are configured to at least partially receive the plurality of cams 133 of the adjustment assembly 130. The tray slots 151 may allow the cams 133 to at least partially rotate within them. In various embodiments, the flat portion 150a includes as many tray slots 151 as the number of cams 133. In an embodiment, the tray slots 151 are dimensionally and functionally identical to the first slots 113 of the liner 110. In another embodiment, the second cam tray slots 151 may be different from the first slots 113 of the liner 110.
[0046] The sidewall 150b of the base 150 is positioned on the circumference of the flat portion 150a. The inner surface of the sidewall 150b includes at least two flat faces 152. The face 152 is provided with a bore 157. The bore 157 is configured to receive the distal portion of the cam shaft 131 of the adjustment assembly 130. In an embodiment, the bore 157 has a circular profile. In an embodiment, the bore 157 is formed on one of the faces 152 to define a shallow slot. Alternatively, the bore 157 may penetrate the sidewall 150b entirely. The bore 157 may have a pre-defined diameter, corresponding to the diameter of the elongated element 131a (shown in Fig. 4) of the cam shaft 131. The diameter may range between 0.5mm and 20mm. In an embodiment, the diameter of the bore 157 is 1mm.
[0047] The sidewall 150b of the base 150 is provided with a plurality of ribs 140 on the inner surface. The number of the ribs 140 corresponds to the number of pegs 111. The ribs 140 are configured to be slidably couple to corresponding one or more the pegs 111 of the liner 110. The ribs 140 and the pegs 111 are slidably coupled. The pegs 111 allow axial displacement and inhibit rotational or angular displacement of the liner 110 with respect to the base 150. In an embodiment, there are two ribs 140. In another embodiment, there may be more than two ribs 140 corresponding to the number of pegs 111. In an embodiment, the ribs 140 have a rectangular profile. In another embodiment, the ribs 140 may have any other profile including, but not limited to circular, square, pentagonal, hexagonal, or any other polygonal profile. The ribs 140 are configured to mate with the pegs 111. At least one surface of the pegs 111 make contact with at least one surface of the corresponding ribs 140.
[0048] One of the ribs 140 is provided with a first hole 153. The first hole 153 is positioned towards the proximal end of the rib 140. The first hole 153 is provided with internal threads (not shown). The first hole 153 may have a predefined diameter. The diameter of the first hole 153 may range between 0.5mm and 20mm. In an embodiment, the diameter of the first hole 153 is 3.5mm. The first hole 153 is configured to receive a plunger 139 of the adjustment assembly 130. In an embodiment, the plunger 139 is provided with external threads. The internal threads of the first hole 153 are configured to mate with the external threads of the plunger 139.
[0049] The other rib 140 is provided with a second hole 159. The second hole 159 is positioned towards the proximal end of the rib 140. In an embodiment, the second hole 159 has a circular shape. In another embodiment, the second hole 159 may have a predefined diameter. The diameter of the second hole 159 may range between 0.5mm and 20mm. In an embodiment, the diameter of the second hole 159 is 3.5mm. The second hole 159 is configured to receive a pin 137 of the adjustment assembly 130.
[0050] The sidewall 150b is provided with an aperture 155. The aperture 155 is positioned on the front of the sidewall 150b. In an embodiment, the shape of the aperture 155 is circular. The aperture 155 is configured to receive a head 131b of a cam shaft 131 of the adjustment assembly 130. The aperture 155 is configured to allow the head 131b to rotate.
[0051] The sidewall 150b is provided with a plurality of markings 155a. Each marking 155a indicates a distinct offset that the trial implant 100 is currently set to. The markings 155a are positioned circumferentially around the aperture 155. The markings 155a are configured to indicate a corresponding offset of the trial implant 100. The number of the markings 155a may correspond to the number of offsets the trial implant 100 can be toggled between. In an embodiment, there are three markings 155a. In another embodiment, there are more than three markings 155a.
[0052] In accordance with Fig. 4, the plurality of components of the adjustment assembly 130 is shown. The adjustment assembly 130 includes a cam shaft 131, a plurality of cams 133, a plurality of resilient elements 135, a pin 137, and a plunger 139.
[0053] As shown in Fig. 4, the cam shaft 131 includes an elongated element 131a and a head 131b. The elongated element 131a defines the body of the cam shaft 131. The elongated element 131a is configured to transfer the rotational input provided at the head 131b to the cams 133. In an embodiment, the elongated element 131a is cylindrical in shape. In another embodiment, the elongated element 131a may have an oval profile. The cam shaft 131 is disposed in the liner 110. The elongated element 131a is placed within the third slot 117 of the liner 110. The elongated element 131a is configured to at least partially rotate within the third slot 117. The diameter of the elongated element 131a may correspond to the width of the third slot 117. The diameter of the elongated element 131a may range between 0.5mm and 20mm. In an embodiment, the diameter of the elongated element 131a is 2mm. The length of the elongated element 131a may correspond with the length of the third slot 117. The length of the elongated element 131a may range between 0.5mm and 20mm.
[0054] The head 131b is provided at the proximal end of the cam shaft 131. The head 131b is configured to receive a rotational input from a suitable tool, to rotate the cam shaft 131. The rotation of the cam shaft 131 causes a change in an axial displacement of the liner 110 with respect to the base 150, thereby adjusting the offset of the trial implant 100. In one embodiment, the head 131b includes a drive socket, configured to engage and be rotated by a key. In an embodiment the head 131b includes a hex drive socket to be engaged and rotated by a hex key. In various other embodiments, the head 131b may include another suitable drive, including, without limitation, a Phillips drive, a tri-wing drive, a square socket drive, a pentagon drive, a pentalobe drive, a Torx drive, or a double square drive, configured to engage and be rotated by a corresponding driver key. It shall be appreciated that the drive types are exemplary, and any suitable drive socket may be used to be engaged with and rotated by a corresponding driver key.
[0055] The head 131b may be coupled to the elongated element 131a using a coupling method including but not limited to pressfit, taperfit, and the like. In an embodiment, the coupling method used to couple the head 131b and the elongated element 131a is pressfit. In another embodiment, the cam shaft 131 may be an integral component with the head 131b at the proximal end and the elongated element 131a at the distal portion, formed as a single piece. The head 131b is positioned within the aperture 155 of the base 150. The head 131b is configured to be rotated within the aperture 155. The head 131b may have a predefined shape.
[0056] The cam shaft 131 is provided with the cams 133. The cams 133 are configured to be rotated when the cam shaft 131 is rotated. The cams 133 are configured to translate the rotational motion of the cam shaft 131 to a linear displacement of the liner 110 with respect to the base 150, thus, adjusting the offset of the trial implant 100. In an embodiment, there are two cams 133. In another embodiment, the number of the cams 133 may be more than two. Another embodiment may include only one cam 133. The cam 133 may have a predefined shape. The shapes of the cam 133 may include without limitation circular, elliptical, and so forth. In an embodiment, the cams 133 have a circular shape. The cams 133 may have a predefined diameter. The diameter may range from 0.5mm to 20mm. In an embodiment, the diameter of the cam is 7mm.
[0057] ¬¬¬¬¬¬The cams 133 are placed within the tray slots 151 of the base 150 and the first slot 113 of the liner 110. The cams 133 are configured to be rotated with in the first slots 113 and tray slot 151. Each cam 133 is provided with a second hole 133a at an eccentric position. The second holes 133a are configured to receive the elongated element 131a. The second holes 133a may have a predefined diameter. In an embodiment, the diameter of the second holes 133a corresponds to the diameter of the elongated element 131a of the cam shaft 131. In an embodiment, the cam shaft 131 and the cam 133 are fixedly coupled via the second holes 133a forming a cam assembly. The cams 133 are arranged uniformly over the length of the cam shaft 131
[0058] The adjustment assembly 130 includes a plurality of resilient elements 135. The resilient elements 135 are configured to keep the liner 110 and the base 150 under a persistent resilient tensile force. In an embodiment, the adjustment assembly 130 has at least two resilient elements 135. In another embodiment, the adjustment assembly 130 may include more than two resilient elements 135. The resilient elements 135 are positioned in between the liner 110 and the base 150. The proximal end of the resilient elements 135 are disposed in the second slots 115. The resilient elements 135 may have a predefined diameter. The diameter of the resilient elements 135 may correspond to the diameter of the second slot 115. The diameter of the resilient elements 135 may range between 0.5mm and 20mm. In an embodiment, the diameter of the resilient members 135 is 5mm. The resilient elements 135 are positioned in between the liner 110 and the base 150.
[0059] The adjustment assembly 130 includes a plunger 139. The plunger 139 is disposed within the first hole 153. The plunger 139 is provided with threads. The threads are configured to mate with the internal threads provided in the first hole 153. The plunger 139 may be employed to lock the liner 110 and the base 150 in a certain position. The plunger 139 is configured to seat the plunger ball 139a at one of the ends. The plunger ball 139a may rotate within the cavity (not shown) provided in the plunger 139. The plunger ball 139a is configured to mate with one of the locking slots 111a, 111b, and 111c to lock the axial displacement of the liner 110 with respect to the base 150 in a certain position.
[0060] One end of the pin 137 of the adjustment assembly 130 is disposed within the second hole 159 of the base 150, being fixedly attached to the base 150. The other end of the pin 137 sits within the slot 112 of the liner 110. The pin 137 moves vertically within the support slot 112. The pin 137 may restrict any motion other than the vertical motion of the liner 110. The pin 137 may have a predefined diameter. The diameter of the pin 137 may correspond to the diameter of the second hole 159. The diameter of the pin 137 may range between 0.5mm and 20mm. In an embodiment, the diameter of the pin 137 is 3mm.
[0061] Fig. 8 depicts an exemplary method 200 of using the trial implant 100. Any method other than the method 200 is also within the scope of the disclosure. The steps may be mutually exclusive or may be dependent on each other. The steps are described in a certain order. Any other order of performing the step that may fulfill the intended purpose of the disclosure is also within the scope of the disclosure.
[0062] At step 201, the trial implant 100 is assembled. As shown in Fig. 5, the cam assembly i.e., the cams 133 and the cam shaft 131 is placed on the flat portion 150a of the base 150. The cams 133 are disposed within the tray slots 151. The head 131b of the cam shaft 131 is disposed within the aperture 155. The distal end of the cam shaft 131 is disposed within the bore 157. The resilient elements 135 are placed on the flat portion 150a parallel to the ribs 140. The plunger 139 along with the plunger ball 139a is disposed within the first hole 153. One end of the pin 137 is partially disposed within the second hole 159 of the base 150. In the end, the liner 110 is assembled with the base 150. The pegs 111 mate with the ribs 140. The other end of the pin 137 is disposed within the slot 112 and the plunger ball 139a is of the plunger is disposed within the one of the locking slots 111a, 111b, and 111c. The disposition of the pin 137 and the plunger 139 within the liner 110 and the tray 150 holds the liner 110 and the tray 150 together. The cam shaft 131 is rotationally coupled to the base 150. The cam shaft 131 is configured to apply an axial displacement force on the liner 110 when rotated. The resilient elements 135 sit within the second slots 115. The cams 133 sit within the first slots 113. (As shown in Fig 6.)
[0063] At step 203, the offset of the trial implant 100 is adjusted. A medical practitioner may removably couple a driver key with the head 131b of the cam shaft 131. The trial implant 100 remains at an initial offset of 0 mm in which includes zero axial displacement of the liner 110 with respect to the base 150 (as shown in Fig. 7a and Fig. 7b. At '0' offset the plunger ball 139a mates with the third locking slot 111c provided on the peg 111. To toggle to the intermediate offsets of 2mm, the cam shaft 131 is rotated using the driver key thereby, rotating the cams 133 within the first slots 113. The cams 133 when rotated, push the liner 110 in an upward direction. The cam assembly (cam shaft 131 and cams 133) is rotated until the plunger ball 139a mates with the second locking slot 111b of the peg 111. Thus, the trial implant 100 is locked in the second offset of 2mm (as shown in Fig. 7c and Fig. 7d). Further rotation of the cam assembly, keeps pushing the liner 110 in an upward direction to finally mate the plunger ball 139a with the first locking slot 111a of the peg 111 to lock the trial implant 100 in the offset of 4mm (as shown in Fig. 7e and Fig. 7f).
[0064] The present description discusses an embodiment with at least three offsets. It should be noted that the disclosure is not restricted to only three offsets. In another embodiment, there may be more than three offsets, or fewer than three offsets. For example, an exemplary embodiment may have 5 offsets at 0mm, at 2mm, at 4mm, at 6mm, and at 8mm.
[0065] The scope of the invention is only limited by the appended patent claims. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. , C , Claims:WE CLAIM:
1. A trial implant (100) comprising:
a liner (110) configured to interface with a prosthetic glenoid ball;
a base (150) configured to be removably coupled to a stem implanted within the humerus bone, the base 150 is slidably coupled to the liner (110); and
a cam shaft (131) disposed in the liner (110),
wherein rotation of the cam shaft (131) causes a change in an axial displacement of the liner (110) with respect to the base (150).
2. The trial implant (100) as claimed in claim 1, wherein:
the liner (110) comprises one or more pegs (111); and
the base (150) comprises one or more ribs (140), the one or more ribs (140) are slidably coupled to corresponding one or more pegs (111);
wherein the one or more ribs (140) and the one or more pegs (111) are configured to allow axial displacement and inhibit rotational or angular displacement of the liner (110) with respect to the base (150).
3. The trial implant (100) as claimed in claim 1, wherein the axial displacement is one of 0mm, 2mm, and 4mm.
4. The trial implant (100) as claimed in claim 1, wherein the cam shaft (131) is rotationally coupled to the base (150), and wherein the cam shaft (131), upon rotation, is configured to apply an axial displacement force to the liner (110).
5. The trial implant (100) as claimed in claim 1, wherein the cam shaft (131) comprises one or more cams (133), wherein the one or more cams (133) are arranged uniformly over a length of the cam shaft (131).
6. The trial implant (100) as claimed in claim 1, wherein the cam shaft (131) comprises a head (131b) configured to receive a rotational input.
7. The trial implant (100) as claimed in claim 6, wherein the head (131b) comprises a drive socket, wherein the drive socket may be one of Phillips drive, a tri-wing drive, a square socket drive, a pentagon drive, a pentalobe drive, a Torx drive, or a double square drive.
8. The trial implant (100) as claimed in claim 2, wherein the peg (111) comprises one or more locking slots (111a, 111b, and 111c), the one or more locking slots (111a, 111b, and 111c) correspond to respective ones of axial displacements of the liner (110) with respect to the base (150).
9. The trial implant (100) as claimed in claim 8, further comprising a plunger ball (139a) configured to mate with the one or more locking slots (111a, 111b, and 111c), to lock the axial displacement of the liner (110) with respect to the base (150).
10. The trial implant (100) as claimed in claim 8 or 9, further comprising a threaded plunger (139) configured to seat the plunger ball (139a).
11. The trial implant (100) as claimed in claim 1, further comprising one or more resilient elements (135) configured to keep the liner (110) and the base (150) under a resilient tensile force.

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